Ink jet recording systems perform recording of images or letters by ejecting ink droplets according to various operational principles and depositing them on recording sheets such as paper. The recording systems have the features that they carry out the operation at high speed, produce little noise, can easily perform multicolor printing, are great in versatility of patterns to be recorded, and require no development-fixation, and the systems recently rapidly spread as recording apparatuses in various uses for recording various figures and color images including Chinese characters. Furthermore, the images obtained by multicolor ink jetting systems are not inferior in quality to the recorded images obtained by the multicolor printing according to plate making systems or the color photographic systems. Moreover, when a small number of prints are to be produced, they can produce the prints more cheaply than the photographic techniques. Thus, ink jet recording systems are being widely applied to the field of full-color image recording.
Recently, cheap ink jet printers which can output highly minute images comparable to images of silver salt photography are commercially available. Ink jet recording sheets can produce images equal in quality to those obtained by silver salt photographic systems and, besides, are very cheap, and, therefore, they provide economically great merit for users who change frequently the images in commercial samples or in advertisement requiring images of large area. Furthermore, according to the silver salt photographic systems, it is utterly impossible to prepare images on personal computers and amend color arrangement or layout with seeing the print out which is recently generally carried out, while such operations can be readily performed by the ink jet recording systems. Under the circumstances, ink jet recording sheets having gloss are increasingly demanded. Moreover, ink jet recording sheets having suitability for carrying out ink jet recording also on back side are marketed, and these are used for photograph-like picture postcards or cards.
As the ink jet recording sheets having high gloss, there are proposed those obtained by using cast-coating method (see, e.g., JP-A-11-48604 and JP-A-2000-85242). Furthermore, a coat is provided on another side of these sheets for imparting suitability for printing by ink jet recording.
However, in the conventional double-side ink jet recording sheets having gloss on one side, scratches sometimes occur on the gloss side owing to rubbing of the gloss side with the opposite side. When they are used for picture postcards or cards, in many cases, a plurality of the sheets are set in a printer and continuous printing is carried out, and scratches are apt to occur. As a result, not only the unprinted portions, but also printed portions are considerably damaged in quality, which is a serious problem.
Furthermore, it is proposed to add organic particles to ink-receiving layer, overcoat layer, back coat layer, etc. (see, e.g., JP-A-2-223466, JP-A-7-25133, JP-A-7-179025, JP-A-11-277881, and JP-A-2001-105722), but these inventions aim at improvement of ink absorbability, improvement of carrying property in printers, inhibition of blocking between the sheets, improvement of water resistance of the ink-receiving layer, and improvement of surface strength of the ink-receiving layer (inhibition of exfoliation), and it has been impossible to inhibit damages on the gloss surface of double-side ink jet recording sheets having one gloss surface side which are caused by rubbing of the sheets with each other.
Moreover, it is proposed to add thermoplastic organic particles to the outermost layer on the gloss surface side, thereby improving scuff resistance (see, e.g., JP-A-2000-158803 and JP-A-2000-203151). However, according to these technologies, ink absorbability tends to deteriorate because the thermoplastic resin is heated in the ink-receiving layer to densify it, and thus it is difficult to satisfy both the ink absorbability and the inhibition of occurrence of scratches on the gloss surface side.
The object of the present invention is to provide a double-side ink jet recording sheet which comprises a paper as a support and has gloss on at least one side and in which there hardly occur damages of the gloss surface side owing to rubbing of the sheets with each other.